dale1983

Whats up guys, I have a ATV turbo project Im working on, the turbo is a t3/t4 hybrid I got from ebay, now for my issues and progress.

Progress: everything is mounted and working.

Issues: I am having a hard time getting it dialed in, it starts fine runs good, but after 1/2throttle it just pops and backfires and sometimes stalls.

What I got: 2001 400ex atv, t3/t4 turbo, mounted with oil lines, charge pipe is straight from turbo to carb "for now", carb vents have been pressurized with turbo. no intercooler, no air plennum yet.

I built a air plennum/ charge box whatever you wanna call it, havent installed yet?

My plug is still white and shows possible slight detonation, even with heavy jetting, could this be causing my backfire/poping?

Will a air plennum help the palpitations in the air and possibly solve the problem? or should I need to retard the timing a bit? or both?

Im very very new at turbos and dont know a whole lot if anything...lol.

It deffinetly is getting more power and working up to the 1/2 throttle point, then falls flat on its face.

What could be going wrong? I need some expert advice and this site has alot of good stuff, but im still stuck at the moment.

Any help is greatly appreciated, thanks for your time.

ssdelsolsi

id think that turbo would be to big and what are you using for fuel management

dale1983

Yeah im worried about the turbo size, others have used similar turbos atleast from what I thought anyway....most used a k03, I thought they were similar but like I said I dont know turbos...lol.

Fuel management, I tried using fuel pumps but they just overflow everything with gas, Ive heard of other fuel devices that pump more fuel with boost, I thought I had that covered with a pressurized carb but....its not working, I dont know what to look for when it comes to fuel management, I guess I would need something small enough for a 400cc carberated engine....dont know where to start?

sc400

find a good ihi ford probe turbo there small and idk if i can post websites but you should look into this
TURBOCHARGER TURBO SMALL ATV MOTORCYCLE BIKE TD03 USED: eBay Motors (item 130400896163 end time Jun-20-10 21:289 PDT) its made for atvs and small stuff

dale1983

Yeah, a couple guys said the ihi was to small? Here's some vids of what Im trying to accomplish.

YouTube - Projet 400ex-t

YouTube - Video of my turbocharged honda 400ex

here is a thread with the same type of quad with a turbo its a tdo4 thats what my turbo says on it.

http://www.exriders.com/vbb/showthre...ghlight=twinty

ATV Riders Forum - the turbocharged 400ex everyone wants to see

I drag race so it compelled me to go faster, right now I run 8.83 in the 1/8th mile, trying to get in the 7s thats why I want this turbo to work.

hope the links worked, hope it will help you guys help me. Thanks for showing interest.

busa4

the problem with boosting a carb'd engine is that when the carb sees boost the carb doesnt flow any fuel. the float bowl is being pressureized and the venturi is being pressured. if float bowl pressure equals venturi pressure there will be no fuel flow causing engine to run lean. this will cause detonation and backfiring and will kill the engine quick.

the fix for this is to add a fuel pump and a boost reference fuel pressure regulator. set the fuel pressure regulator at the stock setting. carbs are usually 5 psi or less. the carb will run at 5 psi under non boost operation. when the engine starts to boost, the fuel pressure will rise. you want the fuel pressure to be higher than boost pressure to allow fuel to flow from the bowl to the venturi. if fuel pressure is 10 psi under 5 lbs of boost then the float bowl will be pressurized at 5 psi causing fuel to be pushed out into the venturi.

tuning boosted carb'd engines is very difficult. its a trial and error method. start off super rich and lean it out to get the desired 11-11.5:1 afr because lean conditions can take out a motor very quickly....

gl with build

dale1983

Thanks thats good info, any advice on a good regulator, exactly what type should I be looking for?

dale1983

Found a bunch on ebay, some are inexpensive? but will an inexpensive one be ok, or is it best to go with a descent name brand? What do you guys usually get for a situation like this? What is a descent brand?....

busa4

ive used many of the cheaper ones with no problems. stick with the ones that are ~75.00 and make sure they cant be adjusted low enough for use with a carb. also make sure they raise pressure with boost.

Clean

An IHI RHF3 or RHB3 would still be a little big IMHO. They're found on suzuki swifts. Back in the day when i used to design Argo's we were going to use it to turbo a 770cc kohler for a high altitude climb.